The present invention relates to seat structures and more particularly to an articulation having a memory of an inclination adjustment position for a seat structure comprising in particular a seat and a backrest which are relatively movable in rotation about at least one axis.
In many industrial fields and for many uses seat structures are employed which comprise in particular a seat and a backrest relatively movable in rotation about at least one axis so as to make it possible to, at will, either progressively incline the backrest relative to the seat to give it a chosen position of adjustment or swing over the backrest for example toward or against the seat and inversely, to a swung over position or to a raised position respectively.
Such seats are employed in particular on tourist motor vehicles, in particular of the "coupe", "convertible" or even saloon type which are provided with only two lateral doors, one on each side of the vehicle. Such vehicles require front seat structures which are either both inclinable at will in accordance with the wishes of their occupants for the comfort of the latter, or retractable in particular by swinging the backrest over toward the seat to facilitate access to whatever is at the rear of the seat structure.
Articulation arrangements for motor vehicle seat structures which allow a progressive, continuous or discontinuous adjustment of the inclination of the backrest relative to the seat are for example disclosed in the documents FR 2 463 596 and FR 2 541 950 and 2 547 778.
Articulation arrangements which permit swinging the backrest over toward the seat are for example disclosed in the documents FR 2 642 377 and FR 93 15 598. All these arrangements have the drawback of being cumbersome and requiring additional components relative to a more conventional articulation employed on saloons having four lateral doors, two per side.
A major drawback of complex articulations which permit both an adjustment of the inclination of the backrest and a swinging over of the backrest, resides in the fact that, upon the raising of the previously swung over backrest to cause it to pass from its swung over position to its raised position, the backrest does not systematically resume the chosen position of adjustment of the inclination it previously had before swinging over, whether this be due to the very design of the articulation or to a false manoeuvre on the part of the user. It is then necessary to effect a new adjustment or touch up the adjustment of the backrest to give the latter its initial position. Such an operation is tedious but is however essential when the seat structure in question is that of the driver.